1. Field
One embodiment of the invention relates to an image processing apparatus, a display device, and an image processing method.
2. Description of the Related Art
Filtering has been performed with an edge-preserving smoothing filter as image processing to remove noise, such as mosquito noise and block noise, from an image. The filtering uses a filter coefficient selected based on a detection result obtained from each pixel block formed of a pixel to be processed and pixels surrounding it. If an edge is present at the boundary of pixel blocks or near the boundary, an appropriate filter coefficient may not be selected, and the edge may be smoothed. In view of this, for example, Japanese Patent Application Publication (KOKAI) No. 2005-79617 discloses a conventional technology in which a filter is selected from a plurality of edge-preserving smoothing filters. More specifically, distortion at the boundary of pixel blocks and the magnitude of the distortion are detected. A pixel range to be filtered is specified based on the detection result, and one of the edge-preserving smoothing filters is selected.
With the edge-preserving smoothing filter, a portion of a pixel block having a smooth image structure may not be sufficiently smoothed. In such a case, it is efficient to perform filtering on a larger pixel block. With the conventional technology, a pixel range is specified based on the presence of distortion at the boundary of pixel blocks and the magnitude of the distortion, and, even if the image structure of a pixel block is smooth, the pixel block is not changed so that filtering is performed on a larger pixel block. Accordingly, efficient filtering is not performed.